OVERALL OBJECTIVES: The overall objective of this project is to provide detailed physiological and biochemical information on selected aspects of the cardiac uptake, storage and utilization of lipids, which are considered to be the primary source of energy for the mechanical function of the heart. The experimental models which have been employed include (a) isolated rat heart in a closed recirculating perfusion system; (b) adult heart cells (a preparation initially developed during the course of these studies); (c) specific subcellular fractions; and where feasible, (d) in vivo studies. GOALS FOR THE CURRENT YEAR: (a) To elucidate the role o lipoprotein lipase in the uptake of triglycerides of very low density lipoproteins (VLDL) by the isolated cardiac myocyte. (b) To determine the apoprotein and lipid compositions of the "remnant" particle(s) obtained following triglyceride removal from VLDL during recirculating heart perfusion. (c) To elucidate the mechanisms of altered VLDL metabolism by hearts from streptazotozin-induced diabetic rats. (d) To initiate studies on the control of and roles of prostaglandin synthesis in isolated cardiac myocytes.